1. Field of the Invention
The present invention relates generally to automated equipment control using inputs based on global navigation satellite system (GNSS) navigation, and in particular to using an automatic steering system to guide between crop rows and against furrow row edges in agricultural applications.
2. Description of the Related Art
Current automated agricultural vehicle guidance and equipment control systems with GNSS-based technology and automatic steering can guide equipment through fields and control their operation with little or no direct human interaction. GNSS-based guidance systems are adapted for displaying directional guidance information to assist operators with manually steering the vehicles. For example, the OUTBACK S™ steering guidance system, which is available from AgJunction LTC (www.agjunction.com) and is covered by U.S. Pat. No. 6,539,303 and No. 6,711,501, which are incorporated herein by reference, includes an on-board computer capable of storing various straight-line and curved (“contour”) patterns. An advantage of this system is its ability to retain field-specific cultivating, planting, spraying, fertilizing, harvesting and other patterns in memory. This feature enables operators to accurately retrace such patterns. Another advantage relates to the ability to interrupt operations for subsequent resumption by referring to system-generated logs of previously treated areas.
Another type of GNSS vehicle guidance equipment automatically steers the vehicle along all or part of its travel path and can also control an agricultural procedure or operation, such as spraying, planting, tilling, harvesting, etc. Examples of such equipment are shown in U.S. Pat. No. 7,142,956, which is incorporated herein by reference. U.S. Pat. No. 7,437,230 shows satellite-based vehicle guidance control in straight and contour modes, and is also incorporated herein by reference. U.S. Pat. No. 7,162,348 is incorporated herein by reference and discloses an articulated equipment position control system and method whereby a working component, such as an implement, can be guided independently of a motive component, such as a tractor. The implement can optionally be equipped with its own GNSS antenna and/or receiver for interacting with a tractor-mounted GNSS system.
Ideally crops would be planted in perfectly straight, evenly-spaced rows. Guidance through such fields would consist of following relatively simple straight-line patterns. Such guidance modes are commonly referred to as straight line or “A-B” in reference to the equipment traveling in a straight line between point A and point B in a repeating pattern in order to cover an entire field, which is typically flat and rectangular and therefore efficiently divided into multiple, parallel swaths. However, field conditions in many areas are not suitable for A-B guidance. For example, hilly terrain sometimes requires the formation of constant-elevation terraces.
Guidance systems accommodate such irregular conditions by operating in “contour following” modes consisting of curvilinear tracks defined by multiple GNSS points along which the equipment is guided. Initial planting passes made with manual and visually-guided navigation, which may or may not be supplemented with GNSS navigational aids, can cause crop rows to deviate from straight lines. Accommodating such irregular crop rows in subsequent operations (e.g., spraying and harvesting) may require the equipment to deviate from straight-line passes.
Notwithstanding recent advances in GNSS-based guidance accuracy, the natural irregularities of row crop cultivation tend to compromise the effectiveness of navigation based solely on location-finding front satellite signals. Moreover, satellite signals are occasionally lost due to interference from atmospheric conditions, weather and electromagnetic fields (EMF). There are various levels of differential accuracy available for GNSS. The use of these can cause offsets and drifts, especially over the crop growth season from field preparation to harvesting. One option to compensate for such lapses in GNSS reception, inertial navigation systems (INS) with gyroscopes has been utilized for relatively short-term, supplemental guidance input.
An alternative concept includes automatic steering control upon collision detection by electrically or hydraulically controlling the physical steering control of the vehicle. Many systems accommodate operators overriding the automated functions. For example, an operator may respond to observed, actual field conditions in order to maintain the equipment on course. Custom applicators, who use their equipment on multiple farms, need guidance equipment capable of universal operation for optimizing their productivity while minimizing crop damage and avoiding vehicle collision on ground that is uneven or otherwise difficult to traverse. Such equipment should be usable by operators with minimal training operating at optimal speeds and should have the capacity for storing and recalling field data for reuse, for example front season-to-season. Higher equipment speeds also tend to create auto-steering discrepancies, which can lead to crop damage from equipment overruns.
Having an automatic steering system which detects user input and automatically disengages the steering system would lead to a synthesis between machine and man, resulting in the best of both worlds. Existing hydraulic steering systems make it difficult to override automatic control when manual control is desired. Such a system can be implemented simply and cheaply into existing machines, as opposed to the more intricate and expensive hydraulic steering systems currently being used.
All-terrain vehicles (ATVs) often utilize electrical steering assist consisting of a worm drive connected to an electrical steering motor for steering over and around obstacles and for power assist, e.g., at low speeds. Such a drive can also be used to provide automatic steering in an agricultural vehicle, with manual over-ride through the use of a built-in slip gear.
Heretofore there has not been available an automatic steering system for an agricultural vehicle with the advantages and features of the present invention.